As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
Using int was a mistake. This patch changes String, StringImpl,
StringView and StringBuilder to use size_t instead of int for lengths.
Obviously a lot of code needs to change as a result of this.
The old implementation tried to move forward as long as the current
byte looks like a UTF-8 character continuation byte (has its two
most significant bits set to 10). This is correct as long as we assume
the string is actually valid UTF-8, which we do (we also have a separate
method that can check whether it is the case).
We can't, however, assume that the data after the end of our string
is also valid UTF-8 (in fact, we're not even allowed to look at data
outside out string, but it happens to a valid memory region most of
the time). If the byte after the end of our string also has its most
significant bits set to 10, we would move one byte forward, and then
fail the m_length > 0 assertion.
One way to fix this would be to add a length check inside the loop
condition. The other one, implemented in this commit, is to reimplement
the whole function in terms of decode_first_byte(), which gives us
the length as encoded in the first byte. This also brings it more
in line with the other functions around it that do UTF-8 decoding.
Utf8View wraps a StringView and implements begin() and end() that
return a Utf8CodepointIterator, which parses UTF-8-encoded Unicode
codepoints and returns them as 32-bit integers.
This is the first step towards supporting emojis in Serenity ^)
https://github.com/SerenityOS/serenity/issues/490
